Batteries in smart keys usually last between 1 to 2 years. There are several possibilities as to why your smart key may last shorter or even malfunction:
The smart key battery may drain faster when put near other electronic devices. These produce an electromagnetic field, interfering with the smart key’s own magnetic field. Avoid keeping it near phones, computers, screens and other electronic devices.
A smart key may not work altogether near strong electromagnetic fields caused by power lines and broadcasting systems. If this keeps happening, you should contact your car dealer for further information.